On May 19, 1992, as the presidential campaign season was heating up, Vice President Dan Quayle delivered a family-values speech that came to define him nearly as much as his spelling talents. Speaking at the Commonwealth Club of California, he chided Murphy Brown — the fictional 40-something, divorced news anchor played by Candice Bergen on a CBS sitcom — for her decision to have a child outside of marriage.

“Bearing babies irresponsibly is simply wrong,” the vice president said. “Failing to support children one has fathered is wrong. We must be unequivocal about this. It doesn’t help matters when prime-time TV has Murphy Brown, a character who supposedly epitomizes today’s intelligent, highly paid professional woman, mocking the importance of fathers by bearing a child alone and calling it just another lifestyle choice.”

Quayle’s argument — that Brown was sending the wrong message, that single parenthood should not be encouraged — erupted into a major campaign controversy. And just a few weeks before the ’92 vote, the show aired portions of his speech and had characters react to it.

“Perhaps it’s time for the vice president to expand his definition and recognize that, whether by choice or circumstance, families come in all shapes and sizes,” Bergen’s character said.

Twenty years later, Quayle’s words seem less controversial than prophetic. The number of single parents in America has increased dramatically: The proportion of children born outside marriage has risen from roughly 30 percent in 1992 to 41 percent in 2009. For women under age 30, more than half of babies are born out of wedlock. A lifestyle once associated with poverty has become mainstream. The only group of parents for whom marriage continues to be the norm is the college-educated.

Some argue that these changes are benign. Many children who in the past would have had two married parents could have two cohabiting parents instead. Why should the lack of a legal or religious tie affect anyone’s well-being?

There are three reasons to be concerned about this dramatic shift in family life.

First, marriage is a commitment that cohabitation is not. Taking a vow before friends and family to support another person “until death do us part” signals a mutual sense of shared responsibility that cannot be lightly dismissed. Cohabitation is more fragile — cohabiting parents split up before their fifth anniversary at about twice the rate of married parents. Often, this is because the father moves on, leaving the mother not just with less support but with fewer marriage prospects. For her, marriage requires finding a partner willing to take responsibility for someone else’s kids.

Second, a wealth of research strongly suggests that marriage is good for children. Those who live with their biological parents do better in school and are less likely to get pregnant or arrested. They have lower rates of suicide, achieve higher levels of education and earn more as adults. Meanwhile, children who spend time in single-parent families are more likely to misbehave, get sick, drop out of high school and be unemployed.

It isn’t clear why children who live with their unmarried biological parents don’t do as well as kids who live with married ones. Adults who marry may be different from those who cohabit, divorce or become unwed mothers. Although studies try to adjust for these differences, researchers can’t measure all of them. People in stable marriages may have better relationship skills, for instance, or a greater philosophical or religious commitment to union that improves parenting. Still, raising children is a daunting responsibility. Two committed parents typically have more time and resources to do it well.

Third, marriage brings economic benefits. It usually means two breadwinners, or one breadwinner and a full-time, stay-at-home parent with no significant child-care expenses. Unlike Murphy Brown — who always had the able Eldin by her side — most women do not have the flexibility afforded a presumably highly paid broadcast journalist. And it’s not just a cliche that two can live more cheaply than one; a single set of bills for rent, utilities and other household expenses makes a difference. Though not necessarily better off than a cohabiting couple, a married family is much better off than its single-parent counterpart.

I’ve been studying single mothers since long before “Murphy Brown” was on the air. In a study I co-authored with Adam Thomas, I put them into hypothetical households with demographically similar unmarried men who, in principle, would be good marriage partners. Through this virtual matchmaking, we showed that child poverty rates would fall by as much as 20 percent in an America with more two-parent households.

In later research, Ron Haskins and I learned that if individuals do just three things — finish high school, work full time and marry before they have children — their chances of being poor drop from 15 percent to 2 percent. Mitt Romney has cited this research on the campaign trail, but these issues transcend presidential politics. Stronger public support for single-parent families — such as subsidies or tax credits for child care, and the earned-income tax credit — is needed, but no government program is likely to reduce child poverty as much as bringing back marriage as the preferable way of raising children.

The government has a limited role to play. It can support local programs and nonprofit organizations working to reduce early, unwed childbearing through teen-pregnancy prevention efforts, family planning, greater opportunities for disadvantaged youth or programs to encourage responsible relationships.

But in the end, Dan Quayle was right. Unless the media, parents and other influential leaders celebrate marriage as the best environment for raising children, the new trend — bringing up baby alone — may be irreversible.

Isabel Sawhill is a senior fellow in economic studies at the Brookings Institution, where she co-directs the Center on Children and Families. She is a co-author, with Ron Haskins, of “Creating an Opportunity Society.”

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